public class B {
    int m, n;
    int[] dx = { 0, 0, -1, 1 };
    int[] dy = { -1, 1, 0, 0 };
    boolean[][] vis;
    char[] word;

    public boolean exist(String[] board, String _word) {
        m = board.length;
        n = board[0].length();
        vis = new boolean[m][n];
        word = _word.toCharArray();
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (board[i].charAt(j) == word[0]) {
                    if (dfs(board, i, j, 0) == true)
                        return true;
                }
            }
        }
        return false;
    }

    public boolean dfs(String[] board, int i, int j, int pos) {
        if (pos == word.length - 1) {
            return true;
        }
        vis[i][j] = true;
        for (int k = 0; k < 4; k++) {
            int x = i + dx[k], y = j + dy[k];
            if (x >= 0 && x < m && y >= 0 && y < n && !vis[x][y] && board[x].charAt(y) == word[pos + 1]) {
                if (dfs(board, x, y, pos + 1))
                    return true;
            }
        }
        vis[i][j] = false;
        return false;
    }
}